as long-term C++ programmer, I'd like to use C++ on ConnectCore 6UL SBC Express board using Digi's BSP. I am using version 2.4r1 of DEY and managed to successfully build and run apix-gpio-example on the board. Now I'd like to use a C++ version of this example, for this I created a hello_world example C++ prokecta and strted adding code. But when linking, the linker complains of undefined symbols:

including #include <libdigiapix/gpio.h> alone is not enough, you need to link with the actual library I think.
you should have something similar to:
CFLAGS += $(shell pkg-config --cflags libdigiapix)
LDLIBS += $(shell pkg-config --libs libdigiapix)